The present invention relates generally to RF high power amplifiers, and more particularly, to circuits for modulating the output signal of an RF high power amplifier.
One conventional RF high power amplifier modulation technique utilizes a series pass switch to toggle on and off a DC bias to the RF high power amplifier. This technique is inefficient since power is dissipated in the switch and its driver. In addition to the switch and driver, the modulation circuitry requires a large quantity of energy storage capacitance on the array and a unique DC bias voltage. These circuits complicate the amplifier, reduce amplifier reliability, and occupy valuable circuit board area. The energy storage capacitance adds a significant weight penalty to the antenna, and is a potential failure mechanism, due to the large amount of energy that is stored.
Accordingly, it is an objective of the present invention to provide for circuits for modulating the output signal of an RF high power amplifier and that overcome the limitations of conventional designs.